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Hot Pipe Bending

Hot Pipe Bending

Shape wood with a propane torch.

By Garrett Glaser


Here's a simple, but effective way to bend thin stock (1/4" thick or less). The only tools you need are a length of 1-1/2" galvanized pipe, a propane torch, a jig to hold them both, and a fire extinguisher–just in case. The pipe is attached to a fl ange through a hole in 3/4" plywood. A jig securely holds the propane torch (Photo, above). This jig rests on the bench and clamps in a vise.

Any woods that take to steam bending are suitable for hot pipe bending, including oak, ash, elm, hickory, beech, birch, maple and walnut. Although there are exceptions, most softwoods and exotic woods are not good candidates. In general, air-dried wood bends more easily than kiln-dried wood. Kiln drying “sets” the adhesive compound between the wood fi bers (called lignin) in a way that makes it resistant to the softening eff ects of heat and moisture. This doesn’t mean kiln-dried wood is impossible to bend; bending it is just more diffi cult.

Always start by making test bends, using extra pieces from the same batch of blanks that you’ve prepared for the real McCoy. Having plenty of extra blanks is important, because you never know where a hidden weakness might lie, and watching a piece break when you don’t have a spare is a real bummer.

Soak in water overnight the pieces that you plan to bend. If you don’t have a large enough container to completely immerse the pieces, wrap them in a soaking-wet towel sealed in a plastic bag.

Ignite the torch, adjust the fl ame to low, and clamp the torch into position on the cradle, with its nozzle 1" or so inside the pipe. It will take a few minutes for the pipe to get suffi ciently hot. Test by dripping water onto the pipe. If the water boils in place, the pipe isn’t hot enough. When the water skitters off , you’re good to go (Photo, top right).

To create a tight curve, slowly rock the strip against the hot pipe with a seesaw motion and apply steady, gentle pressure until you feel the wood relax. Then increase the pressure. When the bend is near the end of the strip, hold the strip with Vise-Grip pliers to protect your hand from the hot (really, really hot!) pipe. To create a larger, more gradual curve, move the strip along the pipe in 1/2" increments, applying fi ve to ten seconds of pressure in each spot, just enough to feel the slightest bend. Check the fi t as you go (Photo, above). To unbend a curve that’s too sharp, simply fl ip the strip over . To make S-curves, work both sides of the strip.

To keep from scorching the wood, lift the strip off the pipe every fi fteen seconds (or any time the surface near the pipe begins to look dry) and quickly rewet it with a sponge before continuing. A little scorching is okay if the damaged surface will be hidden. But scorching can also ruin a piece; at the very least, it’ll require additional sanding.

As with steam bending, springback is likely to occur as the pieces dry. How much the piece moves depends upon a number of factors, including the type of wood used, the character of its grain, and the whims of fate.


This story originally appeared in American Woodworker August/September 2010, issue #149.

August/September 2010, issue #149

Purchase this back issue.

Click on any of the images to view a larger version.

The pipe is ready when water droplets bounce off the surface. If the droplets stick and boil, the pipe isn’t hot enough.


This bending method resembles blacksmithing, because each piece is shaped to fi t, one curve at a time.

 

Handles for Turning Tools

Handles for Turning Tools

Customize their fit for comfort and performance.

By Alan Lacer


Decades ago, woodturning tools came without handles, and turners would simply fashion their own. This makes perfect sense, because a handle that fi ts and feels “right” gives a turner confi dence. And who better to custom-fi t the handle than the person who’ll use the tool?

Turning and installing your own handles is a great exercise in designing, turning to fairly tight tolerances, and drilling wood on the lathe. To get started, you can buy tools unhandled (still an option) or remove their commercial handles (really easy).

 

Use strong, dry wood

Select stock with straight grain, especially for the tool end of the handle (use the strongest grain orientation for this critical area). Traditional hardwoods, many exotic woods, and even local woods that you harvest and dry yourself are all good options. Do not use weak woods such as pine, poplar, butternut, willow, spruce and fir.

Make sure the wood is dry. If you have any doubt about the moisture content, let the handle stabilize for several days (or longer) after roughturning and drilling the initial hole.

I make each handle unique, by using diff erent woods and fi nish colors, so that I can immediately identify each tool. I normally start with stock that’s 1-3/4" to 2" square (Photo 1). The length of the blank depends on a number of factors, including personal preferance and the tool itself. Figure A (below) lists handle lengths that work well for me. It’s always better to make a handle too long, rather than too short.

 

Ferrule stock

Every woodturning tool handle must have a metal ferrule to reinforce the joint between the handle and the tool’s shank, or “tang” (Photo 2). Hardware stores and salvage yards are good sources for ferrule stock. Copper couplings (used to join copper pipe and tubing) are some of the best. They’re available in a variety of diameters and each one can be cut in half to make two ferrules. Choose a diameter that allows plenty of wood between the tool’s shank and the ferrule, usually at least 1/4"–if there’s any question, go with a larger diameter.

 

Make a handle

1. The fi rst step is to drill a 3/8" dia. x 3/4" deep pilot hole for the tang in the blank (Photo 3). Note: If the tang is smaller than 3/8", match the pilot hole’s diameter with the tang. The end you choose for mounting the tang should have straight grain and be free of checks and knots. Clamp the blank in a vise and use a hand-held drill.

2. Install a live center with a cone in the tailstock (see Sources, below). The cone will automatically center the pilot hole when the blank is mounted on the lathe. If you don’t have a cone-type live center, turn a tapered piece of wood to fi t into the blank’s pilot hole and protrude about 1/2" beyond it. When you mount the blank, center the live center’s point on the protruding end.

3. Turn the ferrule end–or the entire blank–to round, using a spindle roughing gouge.

4. Turn a tenon on the end to match the ferrule’s length and inside diameter–go for a driven-on fi t. Slightly taper the tenon’s end to help get the ferrule started. Drive on the ferrule, factory end fi rst, all the way to the tenon's shoulder (Photo 4). This orients the ferrule’s rough-cut end with the end of the tenon. Turn down this rough edge after reinstalling the blank on the lathe. If the edge is very rough, use a mill fi le, off the lathe.

5. For safety, turn a bulb over the part of the handle that will house the tang (Photo 5). This provides maximum strength in the event of a catch or dig-in.

6. Turn the blank to a diameter slightly larger than fi nal size. Then use a detail/spindle gouge to round the back end of the handle.

7. Turn the gripping area of the handle into a shape that you like (Photo 6). Be sure to test the grip with the hand that you will use to control the tool. As the gripping area nears perfection, shape the transition to the bulb to create the optimal feel and balance, but beware of making any portion too thin.

8. Finish-sand the handle and ferrule to 150 grit, with the lathe running. Turn off the lathe and sand with the grain to fi nish the job.

9. Remove the tool rest to drill the tang hole (Photo 7). For round-tang tools, the hole’s depth should be one fourth to one third of the tool’s length. For fl at-tang tools, the hole should house the entire tang—almost to the tool’s shoulder. Mount a Jacobstype drill chuck in the headstock (see Sources) and install an ordinary tapered-point bit (other types of bits won’t enter the pilot hole accurately). Place the handle’s pilot hole against the bit, bring up the tailstock, and lock it. Advance the live center to engage the center hole on the waste end of the tool handle. Put on a fullface shield and set the lathe’s speed between 400 and 600 rpm.

10. Turn on the lathe and check to see that the handle runs true. There should be little or no “ghosting” at the ferrule end. If you see ghosts, stop the lathe and re-center the drill bit in the pilot hole. Once all is running well, take two simultaneous actions to drill the hole: Grasp the spinning handle about halfway back with one hand while cranking the tailstock’s handwheel with the other. Go slowly. If you feel too much resistance, slowly back out of the hole, to remove chips.

11. If the hole must be made larger, to accommodate round tangs that are larger than 3/8" dia., simply repeat the drilling operation, using the appropriate larger taperedpoint bit. Drill stepped holes to accommodate tools with fl at tangs. Drill the small dia. hole the full length of the shank; drill the larger hole only as far as necessary.

12. Finish the back end of the handle off the lathe. Simply cut off the waste with a handsaw and then sand.

13. Set the tool into the handle. This step is critical. I’m a fi rm believer in using epoxy to anchor the tool, so start by pouring a generous amount into the hole. Drive the handle onto the tang (Photo 8). Stop about every quarter of the way to check for alignment—sighting the tool and handle much as you would sight a gun. Look for misalignment left or right and up or down. Tap the tool with the mallet to make corrections.

14. My favorite tool-handle fi nish is the one that comes from hard use: sweat, dirt, wear–and maybe even a little blood. A pure oil fi nish is another option, but any fi lm-forming fi nish (including wipe-on oil-varnishes) will make the handle too slick.


Sources

(Note: Product availability and costs are subject to change since original publication date.)

Oneway Manufacturing, oneway.ca, 800-565-7288, Live Center with Cone (#2 Morse taper), #2064.

Packard Woodworks, packardwoodworks.com, 800-683-8876, Jacobs-Style Keyless Chuck (#2 Morse taper) , #111022.


Fig. A: Suggested Handle Lengths


This story originally appeared in American Woodworker August/September 2010, issue #149.

August/September 2010, issue #149

Purchase this back issue.

Click any image to view a larger version.

1. Choose straightgrained hardwood for the handle. Use brass, copper or steel fittings to make the ferrule, which reinforces the joint between the tool and the handle. Copper couplings make excellent ferrules.


2. Turning tool shanks (or “tangs”) are either round or flat. Both types mount in holes bored in the end of the handle. Flat-tang tools require stepped holes to accommodate their tapered shape.


3. Start by drilling a pilot hole for the tool's tang in one end of the handle blank. Then use a cone-shaped center to mount the blank on the lathe, so the pilot hole will be centered when the blank is turned round.


4. Drive on the ferrule after turning a tenon to fit. This ferrule is a copper coupling that's been cut in half. If the tenon is longer than the ferrule, use another ferrule (the other half of the coupling) to drive the first one home.


5. Turn a bulb directly behind the ferrule, to provide the greatest support for the tool’s tang. Most of the handle’s shaping can be done with a spindle roughing gouge.


6. Shape the handle to fit your grip, gradually and selectively reducing the diameter, until it feels just right. Remove the handle often, to check the way it feels in your hand.


7. Install a chuck in the headstock to drill the tang hole. With the lathe running at slow sped, simultaneously grip the handle (so it doesn’t turn) and crank the tailstock, to carefully drive the handle onto the spinning bit.


8. Drive the handle onto the tang, using a waste block to protect the edge. Check frequently to make sure the tool and handle remain properly aligned.

 

Make Quartersawn Picture Frame Stock

Make Quartersawn Picture Frame Stock

If you’ve got some spare 8/4 (2-in.) lumber lying around your shop, it’s easy to transform it into stunning quartersawn wood for your picture frame. Quartersawn figure in almost every wood is really something special, and quite different from species to species. Even an ordinary piece of thick oak, maple or cherry has a surprise waiting within it.


Mark both ends of a milled 8/4 board with a series of parallel lines that run at right angles to the growth rings. Tilt the blade to match the angle of the first cut—just eyeball it. Move the fence and make the second cut at the same angle.

Next, turn the board around and repeat the same procedure for the other outside edge. Continue to work your way from the outside in, so the last cuts you make are for the center pieces, where your drawn lines are almost vertical.

Click any image to view a larger version.


Return the blade to 90 degrees and saw off the angled edges. Make sure the edge that runs along the fence has the point facing up. If it faces down, it could get trapped underneath the fence. Run the pieces through the planer, and you’re ready to make a very special picture frame.




This story originally appeared in American Woodworker January 2005, issue #112.

January 2005, issue #112

Purchase this back issue.

 

 

Outdoor Finishes

Outdoor Finishes

Simple to Super Durable

by Brad Holden

Outdoor finishes have one thing in common; they all require maintenance. Of course, paint is unequaled at protecting the wood from its two biggest enemies: moisture and ultraviolet (UV) light. Moisture causes the wood to rot, and sunlight bleaches out its natural color. Still, who wants to cover-up beautiful wood with paint? If you want the wood to show through on your outdoor projects, you need a clear finish.

There are three basic clear finishes for outdoor furniture: exterior oil, exterior varnish, and an epoxy sealer with an exterior varnish topcoat. Application ease and service life are the two major differences between these finishes.

Of the three clear exterior finishes, exterior oil is by far the simplest finish to apply. Just flow it on, let it soak in and wipe off the excess. Unfortunately, oil offers the least amount of protection and it must be reapplied every season. Exterior varnish, on the other hand, is more difficult to apply: up to 8 coats have to be carefully brushed on. While exterior varnish offers excellent protection from moisture and UV light, it has to be recoated every few years to maintain that protection. An epoxy sealer with an exterior varnish topcoat is the most durable outdoor finish and can last for many, many years. However, the initial application does take longer then exterior varnish. 

 

Exterior Oil

An exterior oil finish is definitely the simplest, quickest way to treat an outdoor project. On the downside, it will only give you about a year of protection from the ravages of outdoor life. Oil finishes don’t provide a protective film  that sits on top of the wood like varnish does. Instead oil soaks into the wood fibers and dries. Exterior oils have added trans-oxide pigments for UV protection and mildewcides to protect against mold and mildew. You’ll find colors ranging from dark brown to light amber.

Application is simple: a garden sprayer and a rag are all you need. First, flood the surface of your project with oil. I use an inexpensive hand pump garden sprayer. Its fast, easy and only costs about $8.00.  Let the oil soak in according to the manufacturer’s directions, then wipe it off. That’s it. Done! Depending on local conditions, you’ll have to reapply about once per year. The built-in UV protection should keep your wood looking natural for many years (as long as you keep up with the applications).

Click on any image to see a larger version.




 

Exterior Varnish or Urethane

Exterior varnish or urethane (both finishes are technically “varnishes”) builds a protective layer over the wood. It offers superior protection and durability over an oil finish. Often, the term “Spar” is found in the name, but this does not indicate any additional or special ingredient. The term “Spar” originates with its use as a coating for the spars on sailing ships. All exterior varnishes are formulated to protect against moisture and UV radiation.

Exterior varnish is applied with a natural bristle brush in multiple coats. Manufacturers recommend eight thin coats for maximum protection and a deep lustrous finish. Sand the hardened varnish lightly between each coat.

Exterior varnishes cure to a more flexible film than ordinary varnish. The flexible coat is not as likely to crack from seasonal wood movement caused by humidity extremes in an outdoor environment.

Exterior varnish will usually last  2-3 years before it starts to look chalky. As soon as you see a chalky film start to develop, it’s time to freshen the finish. Simply sand the topcoat smooth, and apply a new coat of varnish. Don’t put this important maintenance step off too long or cracks will develop in the finish allowing moisture to penetrate and degrade the wood. That will necessitate a complete strip and refinish to restore the furniture. You don’t want to go there.




 

 

Epoxy with Exterior Varnish

An epoxy sealer with exterior varnish topcoats is the most durable, but also the most labor-intensive finish you can apply to outdoor furniture. This is the finish favored by boat builders so you know it's going to last a long time. Epoxy and exterior varnish enjoy a symbiotic relationship: The epoxy forms an impenetrable moisture barrier that prevents seasonal swelling and shrinking of the wood. This dimensional stability in turn gives longer life to the exterior varnish because it no longer has to stretch and shrink with the wood The exterior varnish returns the favor by providing UV protection, without which the epoxy would rapidly deteriorate.

Apply three thin coats of epoxy. The best way to get thin, even coats is to use a foam roller cut in half. It works kind of like a squeegee. Epoxy cure times vary depending on their formulation and the ambient temperature. Be sure to use an epoxy with a long enough open time (approximately 30 minutes), so it doesn’t set up before you’re done putting it on. For large projects, mix the epoxy in small batches so you can finish an area before the epoxy sets. Also, for optimal flow out and penetration into the wood fibers, make sure the epoxy you use doesn’t contain any thickeners. Always read and follow the instructions that come with your epoxy. If possible, apply the epoxy undercoat prior to assembling the parts. You can recoat without sanding while the previous coat is still soft but not sticky. If the epoxy seems uneven or bumpy, allow it to harden. Then, sand it smooth and apply the next coat.

Before applying the varnish topcoats, I use a card scraper or sanding block with100 - 120 grit sandpaper to level the cured epoxy (see photo below left). The sanded surface also provides some tooth for the spar varnish to adhere to.

Rinse the sanded epoxy with clean water and dry with paper towels. The rinse water should not bead on the surface. Beading indicates that contaminants from the epoxy curing process are still on the surface and could interfere with the varnish bond. To remove the contaminants, wipe down with mineral spirits and dry with paper towels or a rag. Follow this with eight coats of exterior varnish, sanding lightly between coats.

 

Sources

Source information may have changed since the original publication date.

Epoxyheads, epoxyheads.com, 866-376-9948, epoxy resin #7710 $33.00/qt; epoxy hardener #7720 $17/ 1/2 pt.; metered pump set #7801 $11.

Penofin, penofin.com, 800-penofin, Original Blue Label Oil Wood Finish, $15/qt.

Home Depot, homedepot.com, 48 oz. Chapin multi-purpose hand sprayer model 1002 $8.

Home center/hardware stores, exterior oil varnish or urethane.

 

This story originally appeared in American Woodworker April/May 2007, issue #128.

 

April/May 2007, issue #128

Purchase this back issue.




1. Sand out any unevenness and defects in the cured epoxy before applying the exterior varnish topcoats.




 

Foolproof Scraper Sharpening

Foolproof Scraper Sharpening

Make shavings like a pro with our new sharpening method.

By Tom Caspar

Scraping is quiet and efficient. It’s perfect for removing milling marks and shallow tear-out. I couldn’t believe my eyes the first time I saw John Erickson, the woodworker I apprenticed with, scrape a piece of walnut. How could a mere piece of steel work so quickly? John didn’t have to go through five grits of sandpaper to get a smooth surface. He’d take a board right from the jointer, scrape a few strokes, lightly sand with the finest paper, and that was it!

I was only a young apprentice in his shop. When it came time for me to sharpen my own scraper, all I got was dust, not those long shavings John made. How did he do it?

Although the old man never shared his sharpening system with me, I’ve developed my own approach using some modern twists. The best thing about it is that anyone can get great results. Once you get the hang of it, you can put a fresh edge on a scraper in five minutes, tops. All you need is some basic sharpening equipment, the world’s simplest jig (a plain stick with one beveled side), a vise on the front of your bench and the patience to take the process one step at a time.




What you need


The Scraper

A card scraper is a rectangular piece of flat steel. Like a handsaw blade, the steel is soft enough to be filed, but hard enough to hold an edge. Scrapers have four cutting edges shaped like miniature hooks. The hooks are almost too small to see, but you can feel them with your fingers.

In the steps that start on page 4, we only tackle the top side of the scraper, making two cutting edges. To sharpen all four edges, flip over the scraper and repeat each step on the bottom side.

Click any image to view a larger version.



The Sharpening Kit

File. The handiest tool is a 10-in. combination mill file with a built-in handle. The double-cut side of the file has two crisscrossed rows of teeth for fast stock removal. The single-cut side has a single row of teeth. This side cuts slower but leaves a smoother surface. Actually, any 8- or 10-in. mill file will work, as long as it’s sharp.

Honing Paddle. A diamond paddle cuts fast and stays flat. You can substitute a slipstone or small oilstone, but they’re slower and score too easily. An extra-fine grit paddle is best, but a fine will work.

Burnisher. A burnisher is nothing more than a hardened and polished 3/8-in.-dia. steel rod. Most come with a handle, but you really don’t need one.

File Card. A file card cleans your file. If you don’t routinely clean your file, metal debris caught in the file’s teeth will put deep scratches on a scraper’s edge.

Oil. Honing oil lubricates the burnisher. Household oil (such as 3 IN 1) works, too, but leaves your hands smelly. See Sources, below, for information on where to buy these items.



The Jig

This beveled stick is all you need to hold the file, honing paddle and burnisher at the correct angles.




Flatten the Dull Hooks

Stroke the burnisher back and forth over each edge of a dull scraper. Smear a few drops of oil on the burnisher first, then press down lightly and rub until you no longer feel a hook. Two or three passes should do it. Hold the burnisher flat on the scraper, or lean it over the edge, as shown.




Remove the Dull Edge

Push the coarse, double-cut side of the file down the full length of the scraper. Removing lots of metal is the key to success. Hold the scraper in a vise. Ride the knuckles of your hand along the benchtop to steady the file at about 90 degrees. You don’t have to be precise, just aggressive. Don’t drag the file back over the scraper on the return stroke, though, or you’ll prematurely dull the file.




Test for Sharpness I

Feel for a very small ridge of excess metal on both sides of the scraper. This ridge is called a wire edge. Pay special attention to the center section of the scraper, where it’s the dullest. If you feel a wire edge here, move on to Step 4. If you don’t, go back to Step 2.




Remove the Wire Edge

Hone both sides of the scraper with the diamond paddle. Hold the paddle so most of its face is riding on the scraper’s side. Hone back and forth until you no longer feel a wire edge. It should only take a few strokes. Wipe the paddle on a damp rag to keep it clean and cutting efficiently.

Caution: Hold the paddle carefully so you don’t cut your fingers on the scraper’s sharp edge.




Level the Scraper with the Jig

Adjust the scraper in the vise so the full length of its top edge feels even with the jig stick. Make sure the beveled side of the stick faces away from the scraper.




File the Edge Square

File the edge again, this time using the finer, single-cut side. Support the end of the file with the jig stick. This guarantees that you’ll make a 90-degree edge. Keep filing until you feel a faint wire edge on both sides, just like in Step 2.

Pushing the file at about 120 degrees is called draw-filing. This produces a smoother edge than pushing the file in line with the edge, as shown in Step 2.




Hone the Edge Square

Support the honing paddle with the jig stick to maintain a perfect 90-degree edge. Then hone both sides of the scraper, as shown in Step 4. Alternate honing the sides and the top four or five times. This is the only way to completely remove the wire edge.




Test for Sharpness II

Check the edge to make sure it’s sharp. Pull your thumbnail across the center and both ends of the scraper. If you see small shavings, and the center feels as sharp as the ends, you’re ready to go on to the next step. If not, repeat Step 7.

Caution: The edge and corners are very sharp!




Bend the Hook In

Burnish the edge into a concave shape. Remove the scraper from the vise and lubricate the burnisher with a few drops of oil. Then lean the burnisher about 5 degrees and stroke it back and forth over the scraper’s edge three or four times. Press hard with your thumb directly over the edge. Flip the scraper over and burnish the other side.




Bend the Hook Out

Bend the cutting hook using the jig stick as a guide. Clamp the scraper back in the vise so it’s level with the lower edge of the stick’s bevel. Push the burnisher back and forth four or five times, applying hard pressure.

When you’re done with one hook, place the jig stick on the other side of the scraper and repeat to form the second hook. As you gain experience in burnishing, you’ll find that you won’t need a guide to get the angle right.




Try it out

Bend the scraper to stiffen the cutting edge. Place your thumbs near the bottom edge and pull back the ends with your fingers. Lean the scraper forward and push with your thumbs. It may take a bit of experimentation to figure out how much lean you’ll need to make full-fledged shavings.

 

Re-sharpening a Dull Scraper

When you’ve worn out all four edges of your scraper and all you get is dust, not shavings, it’s time to reburnish the edges. Chances are the hooks aren’t dull, but simply bent back. To re-form the hooks with your burnisher, repeat Steps 9 and 10. This usually works two or three times, but eventually the hooks get worn away and can’t be re-formed. Then it’s time to get out the file and start from the beginning.




Sources

(Note: Product availability and costs are subject to change since original publication date.)

Woodcraft, woodcraft.com, 800-225-1153, Sandvik card scraper, #02Z08; Honing oil, #07D10.

Hock Tools, hocktools.com, 888-282-5233, Burnisher, #BR375.

doityourself.com, 866-835-5643, 8" Nicholson Handy File #06601; File card #22284;

EZE-LAP, eze-lap.com, extra-fine honing paddle, #LSF.


This story originally appeared in American Woodworker September 2003, issue #102.

September 2003, issue #102

Purchase this back issue.

 

 

Make Poplar Look Pretty

Make Poplar Look Pretty

Give this useful but unattractive wood a makeover.

By Kevin Southwick


The wood we know as poplar has many common names, such as tulip poplar, yellow poplar, tulipwood, yellow tulipwood, tulip tree, whitewood and canoewood. The “tulip” part of these names comes from the tulip-like flower the tree produces in the spring. Where the “poplar” part of these names comes from is a mystery, because the tree is not even a true poplar—it’s a member of the magnolia family. In fact, poplar is known as the “king of the Magnolias.” It’s also the tallest hardwood tree in North America.

Regardless of what it’s called, Liriodendron tulipifera Magnoliaceae produces very useful and versatile lumber. The tree grows fast, with a straight trunk and no branches near the ground. That translates to knot-free boards that are available in expansive widths and thicknesses. Poplar is economical, costing considerably less than other hardwoods such as maple and oak, and its finely textured lumber works well with both hand and power tools. These qualities make poplar suitable for many furniture and construction applications.


An ugly duckling

So why isn’t poplar popular with furniture makers? The answer is simple: The wood is just plain homely. Its color ranges from pale yellowish white to an odd shade of green, and boards are often discolored by dark gray or purplish streaks. To top it off, poplar doesn’t stain well with traditional wood stains. In fact, it can get ugly really fast because it blotches so easily. About the only time furniture makers use poplar as a primary wood is when the piece is going to be painted.

 

Transformed

Poplar has too many desirable furniture-making qualities to be limited to “paint-grade” service. Fortunately, by using a special approach, it’s possible to make this ugly duckling glow beautifully. This process will transform poplar’s odd green color to any brown wood tone you like. However, dark streaks will still show—they’ll need to be avoided or placed strategically in the design and called “character.”

The key to giving poplar a rich, even stain color is to control its horrible blotching tendencies. This requires starting with a very effective stain controller (also called wood conditioner or pre-stain sealer). The commercial stain controllers I tested didn’t provide enough blotch resistance, so I developed a simple recipe to make a controller with the necessary strength. This recipe and the finishing steps that follow work well on any wood that’s prone to blotching.

After applying the stain controller, use a two-step coloring process for better control and color intensity. This coloring method combines the benefits of both dye and pigment stain. The dye provides a ground color as strong and rich as needed, and the pigment ensures that the color doesn’t fade and become dull over time. The dye and pigment colors shown here are both a medium-dark “warm” brown. They combine to create a rich chocolaty tone on both the green heartwood and pale sapwood. Your color choices may be different.

 

How-to

1. Prepare the surfaces by sanding to 180 grit. Be sure to sand by hand after you power sand, to eliminate swirl marks. Pay extra attention to the end grain.

2. To make the stain controller, mix one part General Finishes Clear Gel Varnish with three parts paint thinner. Apply the stain controller with a rag and allow it to soak in (Photo 1). Be sure to saturate the wood, especially the end grain. After a couple of minutes, but before the stain controller starts to set up (5-10 minutes), use clean, dry rags to remove any that has not soaked in. Be sure not to leave any wet spots or streaks—they’ll show up when you apply the stain. Let the wood dry overnight. This step is intended to seal the wood approximately 60%-75%, which is usually enough to control blotching and still allow the stain to penetrate.

3. Wash the partially sealed surface with a mixture of dish soap and water to “open” the top layer of wood cells so they’ll absorb the dye easily (Photo 2). This step won’t cause any significant grain-raising because the surface has been treated with the stain controller.

4. Hidden blotches will reveal themselves as the water dries (Photo 3). Areas that are extra-porous soak up more water. This means they’ll stay wet longer, so they’re easy to identify. The longer they stay wet, the worse the blotch will be. Fortunately, even super-absorbent areas can be tamed if they’re found and treated with extra stain controller before color is applied.

5. Mix TransFast Medium Brown Water Based Dye following the label instructions and apply it generously, using a rag (Photo 4). Allow the dye to saturate the wood, then remove the excess with clean rags. Allow the wood to dry until the water has completely evaporated (2 hours).

6. Check the workpiece and selectively apply clear gel to any blotches or end grain that are already dark enough from the dye step (Photo 5). This is your last chance for blotch reducing.

7. Apply a coat of General Finishes Medium Brown Gel Stain (Photo 6). Then let the piece dry overnight.

8. Apply two coats of 2 lb. cut amber shellac (Photo 7). Although shellac is a durable finish, I know that this table will often be used as a place to rest a coffee cup, so I’ll add a coat of oil-based satin polyurethane to prevent water rings.


This story originally appeared in American Woodworker October/November 2010, issue #150.

October/November 2010, issue #150

Purchase this back issue.

Click any image to view a larger version.

1. Start by wiping on a strong stain controller to keep the poplar from blotching when you apply the dye and stain. Make a strong stain controller by thinning gel varnish with mineral spirits.


2. Wash the sealed surface with soap and water so the dye will soak in, rather than bead up on the surface.


3. Blotch-prone areas will stand out as the water dries, because they’re super-absorbent. After the wood has thoroughly dried, apply an additional coat of stain controller to these areas.


4. Apply a coat of medium-brown dye to create a uniform ground color.


5. Look again for blotching or dark end grain. Seal any areas that have gone extra-dark with a coat of gel varnish just before you apply the gel stain in the next step.


6. Apply a coat of medium-brown gel stain. Gel stain adds richness to the overall color and helps to keep the dye from fading.


7. Apply two coats of amber shellac to add depth and tone, followed by a more protective topcoat, if necessary.


Turn green to gold

Oxalic acid works miracles on poplar’s green heartwood. Simply mix a saturated solution of oxalic crystals in hot water and brush the solution on the wood. As the solution dries, the green heartwood will turn to a golden brown and the white sapwood will take on a warmer shade of pale. A second application of the solution after the first has thoroughly dried usually helps the results—and it can’t hurt. Oxalic acid is poisonous, so let the surface dry completely and then rinse it thoroughly with water to remove any acid that remains. Note that this treatment does nothing to reduce poplar’s tendency to blotch, so you’ll still need to follow the recipe to end up with a great-looking finish.

Oxalic acid is primarily used to restore the natural color of grayed, weathered, exterior wood—it’s the active ingredient in deck-renewing products. Restorers and woodworkers use oxalic acid to remove black water stains from wood. It’s available at most hardware stores.

 

Turning Wood: Socket Chisel Handles

Turning Wood: Socket Chisel Handles

Here’s a 1-2-3 system for getting a perfect fit.

By Tim Heil


High-quality socket chisels— such as the Stanley Sweathearts and Lie- Nielsens—are making a big comeback. Why would these companies choose the socket style? Well, it’s all about you, the user. If you’re not satisfi ed with a handle’s shape, you can change it. If you want a diff erent wood—no problem. Th e handle of a socket chisel isn’t glued or fastened to the tool, so you just remove it and make your own.

Truth is, woodworkers have been doing this for years. In the age before plastics, when a wood handle on a socket chisel split or mushroomed, replacing it was easy. But not all were fixed. Today, there are loads of wonderful old socket chisels going for a song, merely because they have busted or missing handles.

I’m a turner with a thing about handles— I just love making them. Screwdrivers, awls, ice cream scoops: If it’s got a handle, I’ve got to make my own.

When I first turned handles for socket chisels, I would make a few crude measurements of the socket and just go at it. If the taper on the handle’s shank wasn’t quite right, I guessed where it was off and tried again. While this method works OK, I’ve since found a measuring system that’s much more reliable. Following these steps, your shank should fit tight right away.

First, turn a cylinder that’s an inch or two longer than the length of the handle you’re going to make (of course, the full length includes the shank). Th e narrow end of the shank will most likely be a small diameter (anywhere from 1/4" to 3/8"), so I prefer using a cone-shaped revolving center in the lathe’s tailstock. Th is gives me more room to maneuver the parting tool when cutting the shank’s taper.

 

Measure the socket

Start by wrapping a small piece of notebook paper around a pencil, forming a cylinder (Photo 1). Push the cylinder all the way down into the chisel’s socket (Photo 2) and let the paper unroll into a cone. (You may have to help it a little bit.) Once the paper has fully conformed to the socket’s taper, put a couple of pieces of tape on the paper, to hold its shape. Th en draw a line on the cone, following the top of the chisel’s socket (Photo 3). Remove the cone—you’re all set to take three measurements.

First, set a divider to the distance between the pencil mark you made and the end of the cone (Photo 4). Transfer that distance to the handle blank (Photo 5). Second, set a caliper to the diameter of the cone at the pencil mark (Photo 6). Turn the blank to this diameter, immediately to the right of the mark indicating the shank’s length (Photo 7). (I fi nd it easier to do this if I start roughing out the shank at the same time.) Th ird, reset the caliper to the diameter of the cone’s end (Photo 8). Turn the end of the shank to this diameter (Photo 9), then form a straight taper up to the end of the shank.

 

Test the fit

If all has gone well, the shank should perfectly fi t the socket. Just to be sure, perform a simple test. Rub a piece of chalk on the inside of the socket (Photo 10). Turn off the lathe, pull away the headstock and push the socket onto the shank. Twist the chisel a few times and remove it (Photo 11). If the fi t is correct, most of the shank will be coated with chalk; if it’s not, the chalk will show you the high spots that need to be removed. If the fi t is too loose, your best bet is to cut off part of the shank and start over from the beginning. Don’t worry—the turning goes pretty quick.

Once the fi t is OK, lengthen the shank by about 1/8" (Photo 12). (Notice the small gap between the end of the socket and the end of the shank on the handles shown on page 30.) Th is gap allows you to drive the shank tight into the socket. Th e end of the handle shouldn’t butt up against the top of the socket. If it does, the handle could split when you strike the chisel.

Turn the handle to any shape you wish (Photo 13). Th ere’s really no right or wrong here; traditionally, chisel handles came in many diff erent shapes and sizes. If your work requires you to strike the chisel hard, you may want to put a ferrule on one or both ends of the handle to prevent it from splitting. Turn off the lathe from time to time and test how the handle feels. When you’re done, part off (Photo 14). To install your handle, just drive it into the socket with a mallet. With a tight fi t, there’s no need for glue. When you apply fi nish to the handle, don’t put any on the shank. If the shank is too slippery, it won’t stay seated in the socket.


This story originally appeared in American Woodworker February/March 2012, issue #158.

Click any image to view a larger version.

1. Chisel sockets come in many different sizes, so you’ll need to take some measurements before turning the handle. Start by cutting a piece of notebook paper about 4” square. Roll it up around a pencil.


2. Push the paper cylinder all the way into the chisel’s socket. Let go of the paper—it will unroll to form a cone. The cone will be exactly the same shape as the socket.


3. Stick one or two pieces of tape on the cone to hold its shape. Mark the cone at the end of the socket. Remove the cone from the chisel.


4. Set a divider to the distance between the pencil mark and the end of the cone.


5. Mark this distance from the tailstock end of a blank you’ve roughed out.


6. Set a caliper to fit the cone at the mark you drew at the end of the chisel’s socket. This will be the major diameter of the handle’s shank (the part that fits into the socket).


7. Turn the blank to the major diameter, just to the right of the pencil line. Rough out the rest of the shank’s taper.


8. Reset the caliper to fit the end of the cone. This will be the shank’s minor diameter.


9. Turn the end of the shank to the minor diameter, leaning the parting tool at about the same angle as the rough taper. Cut a straight taper between the major and minor diameters.


10. Check the fit of the shank in the chisel’s socket. First, coat the inside of the socket with chalk dust. Then turn off the lathe and pull away the tailstock.


11. Push the socket onto the shank and twist it a few times. If its taper is correct, the full length of the shank will be coated with chalk. If it’s not correct, only the high spots will be coated.


12. Once the taper is correct, lengthen the shank about 1/8" to the left.


13. Shape the rest of the handle as you wish. Stop the lathe and remove the handle from time to time to test how it feels.


14. Part the handle from the blank using a spindle gouge. (My gouge is very short, from turning so many handles!)


 

Chemical Ebonizing

Chemical Ebonizing

A sure-fire recipe for turning any wood deep black.

By Richard Tendick


Remember the old slogan, “better living through chemistry”? When it comes to turning wood black—a process called ebonizing—I prefer the chemical approach, which uses solutions made from vinegar, steel wool and tannic acid. Watching them transform an ordinary wood, such as the yellow poplar I’m using here, is magical.

Other methods of ebonizing (dye, ink and paint) use pigments, which can obscure the wood’s grain. The chemical technique leaves an absolutely transparent layer of black. You can still see the wood’s figure and character, particularly after you apply a topcoat.

Woodworkers have long known that rusty, acidic water turns some wood black. Woods that are high in tannic acid, such as oak, walnut and mahogany, work best. The technique I’ll show you adds tannic acid to the wood, so you can ebonize virtually any species. I can’t take credit for this idea, though; it’s been a finisher’s trick for a long time.

 

Mixing the chemicals

The two solutions can be stored and used over and over. The first is more or less liquid rust, which you make with white vinegar and steel wool (Photo 1). For the best results, use Heinz white vinegar and Liberon 4/0 steel wool (see Sources, page 63). This steel wool works well because it doesn’t contain oil, but you could also use regular steel wool and wash out its oil with a detergent. Cover the jar with a lid, then puncture the lid with a small hole to let gas escape. Set the jar aside for a week or so.

Eventually, the pad will dissolve and the formerly clear liquid will turn a dark reddish brown, with a black scum on top. Place a coffee filter in a funnel and pour this gunk through the filter into a new container. Repeat the process two or three times, using new filters, to remove all the solids from the solution.

The second solution, tannic acid, is made with dry powdered tannin (see Sources, below). It’s not expensive, but unfortunately it’s not available in a small quantity. Rather than be stuck with a lifetime’s supply, I’ve shared the surplus with a dozen woodworking friends.

To mix the powder, place 1 heaping tablespoon in a disposable container and add a small amount of water (Photo 2). Stir until the powder forms a paste, then add 1 pint of hot tap water. Transfer the solution to a jar or bottle. It can be used right away.

The next step is to raise the wood’s grain with plain water (Photo 3). This is important to do now, before applying either solution, because you won’t be able to sand the wood during the ebonizing process. After the wood dries, sand off any fuzz you may feel with 280 or 320 grit paper (Photo 4). I usually repeat this process two or three times.

 

Application

It’s clear sailing from here. First, pour a small amount of the tannic acid solution into a shallow container and brush it on your project (Photo 5). Make sure every bit of the surface is covered. Let the wood dry.

Next, pour a small amount of the steel wool and vinegar solution into a separate container. Using a different brush, apply the solution to the wood (Photo 6). Almost immediately, the wood will turn a bluish black. Don’t pour the excess solution back into your original container, as it will be contaminated by the tannic acid. Again, let the wood dry. Finally, apply another coat of tannic acid, using a rag to avoid brush marks (Photo 7). Voila! You’ll get a rich, deep black.

Dispose the surplus tannic acid (it will be contaminated, too), and let the wood dry a day or two. You’re ready to apply a clear finish.


Sources

(Note: Product availability and costs are subject to change since original publication date.)

FinishSupply.com, shellac.net, 707-226-3623, Dry Powdered Tannin, 8 oz.

Highland Woodworking, highlandwoodworking.com, 800-241-6748, Liberon 4/0 Steel Wool, 100g.


This story originally appeared in American Woodworker October/November 2010, issue #150.

October/November 2010, issue #150

Purchase this back issue.

Click any image to view a larger version.

1. Dissolve steel wool in vinegar to make the first of two solutions you’ll need. The pad should completely dissolve in about one week.


2. Make tannic acid for the second solution. Mix dry powdered tannin with a small amount of water to make a paste, then add more water.


3. Raise the grain before you begin the ebonizing process. Wet the wood’s surface with a damp rag or sponge.


4. Sand with fine paper to remove any fibers sticking up from the wood’s surface.


5. Brush on the tannic acid solution and let it dry.


6. Apply the vinegar and steel wool solution. The surface will turn a bluish black right away.


7. Apply more tannic acid with a rag. This turns the wood a deep, transparent black. After it dries, you’re ready for a topcoat.

 

Spalted Wood

Spalted Wood

By Alan Lacer


When wood is captured somewhere between the extremes of being completely sound and fully rotten, it can display magnificent beauty. The discoloration, prominent black lines and changes in texture that occur during the decaying process are known to woodworkers as spalting.

Spalting is a by-product of the rotting process that is carried out by a vast army of stain, mold and decay fungi. They are abundantly present in the air and soil, waiting for favorable conditions and a suitable host. Generally, wood moisture content of at least 25 percent, temperatures from about 40- to 90-degrees F, air and food (especially abundant in sap wood) are what the fungi need. A tree or branch freshly fallen onto a damp forest floor in warm weather is asking for it.

Lighter colored woods offer the best canvas for nature’s graphic work. Hard maple is viewed as the king of spalted woods, although sycamore, persimmon, red and white oak, elm, pecan, birch, buckeye, apple, magnolia, beech, holly, hackberry, box elder and the sapwoods of walnut and cocobolo are favored by woodworkers as well.


Where to find spalted wood

You can purchase spalted wood—usually maple—from specialty lumber and mail order suppliers (see Sources, below). Turning blocks are most easily found, but a few suppliers offer boards when they can get them.

Hunting spalted wood is like panning for gold—lots of searching for that one precious nugget. Logs rotting on the forest floor, dead limbs and entire dead standing trees are excellent sources. You can also hunt for hidden treasure at a community bone yard of removed trees, and don’t overlook the bottom of your old firewood pile.


Make your own spalted wood

Woodworkers commonly use these methods to cause wood to spalt. They will work most effectively if the temperature is kept where the fungi will thrive, between 60- and 80-degrees F. Monitor the spalting progress monthly—the optimal conditions you’ve created can make it happen fast.

• Place a freshly cut log section 2 to 3 ft. long upright on the bare ground. Put a shovel of dirt on the top end and cover it loosely with black plastic.

• Bury a log, freshly sawn green boards or green rough-turned bowls in damp sawdust containing pieces of rotten wood with active fungi. Keep the sawdust moist.

• Use plastic bags or plastic garbage cans to hold short sections of green wood or rough-turned bowls. Adding some soil or rotting sawdust may speed the process, although the fungi already present in the air or on the wood surface is probably enough to get it going. Leave the bags or cans with a small opening to allow for some air exchange.


How to stabilize spalted wood

Remove those things the fungi need to grow, and you’ll stop its progress. One method is to lower the wood’s moisture content.Wood below 25-percent moisture content, when kept in low relative humidity, is not likely to decay or even stain. Accomplish this by air or kiln drying, placing smaller pieces in a microwave or finish turning if the piece was a rough-turned bowl. You can also raise or lower the wood’s temperature. Spalting rarely occurs above 90-degrees F and stops below 32-degrees F. Some turners store blanks in a freezer prior to finish turning. Finally, you can restrict the air—no air, no decay. Logs submerged in water, for example, do not decompose from fungi. Tightly wrapping the wood in several layers of plastic will restrict the air and slow the growth of the fungi.

 

Working properties

If you’re lucky, you’ll catch the spalting at the right time, before the cellular structure of the wood deteriorates, and you’ll be able to work the piece without any trouble. Sometimes, however, the material will have areas that have become soft and punky. These areas have no strength and defy normal woodworking strategies. They will crumble, tear out in chunks or leave a wrinkled appearance when you try to cut or plane them. They refuse to be glued together, and leave you with a cratered, uneven surface when you try to sand. Though not suitable for joinery, these soft areas can often be stiffened enough to finish so the piece of wood can still be used decoratively.

You can saturate soft areas with a liquid hardener. Where the wood is only marginally soft, a spot coat or two of clear shellac or nitrocellulose sanding sealer may harden it sufficiently. A really punky spot will require cyanoacrylate (CA) glue (the thin, watery type) or a product made to stabilize rotten wood. There are a number of them sold as wood hardeners at hardware stores. It may take several generous applications to treat each bad spot. These hardeners are effective, but they have side effects. They fill the wood cells, so surfaces treated with them can’t be glued and oil finishes don’t take well because they can’t penetrate. Solvent-based hardeners and CA glues darken the wood considerably. I like Protective Coatings Petrifier (see Sources, below). It’s a water-based hardener that doesn’t discolor the wood, yet seals and stiffens effectively. It’s an excellent choice for troublesome soft spots.

You should be able to work the stiffened surface with edge tools—make very light cuts—or with abrasives, taking care to provide a firm, flat backing for the sandpaper. Some turners use body grinders or stiffbacked sanding discs and work the piece while it’s spinning on the lathe. For flat lumber, an abrasive planer is an excellent option, followed by a randomorbit or pad sander. If you sand by hand, use a sanding block to give firm support to the paper.

 

Finishing

You are likely to encounter three problems when you finish spalted wood: Splotching, yellowing and excessive darkening. The whiter woods—which usually have the most dramatic examples of spalting—can turn quite yellow with certain finishes, and because the soft areas act like end-grain or even a sponge, splotching or excessive darkening can result unless the piece is sealed first. An effective weapon against splotching is clear, dewaxed shellac used as a sealer. (Spray cans of shellac are thinned and dewaxed.) Cover the entire piece with a thin coat and let it dry. Then recoat dull-looking areas until all surfaces have a uniform sheen. You can use almost any finish as a topcoat over dewaxed shellac after it’s been sanded.

To minimize yellowing and darkening, use a surfacefilm finish like clear shellac or lacquer. Waterborne finishes dry clear and don’t yellow with age. If the piece is primarily decorative and has few, if any, soft areas, clear wax is appropriate.

If you don’t mind the yellowing and darkening, use your favorite oil finish, but be prepared to make many applications to the softer areas. Experience has taught me that an oil-finished spalted piece will appear rather muddy and uneven at first, but will look better as the finish cures, which can take weeks or even months. Some oil finishes (such as General Finishes Sealacell Step 1, see Sources, below) are essentially a thinned, light-colored varnish, and will not yellow as much.

If you are looking for a challenge, and effects that often surpass the wildest woods from the tropics, spalted wood may be your ticket. Each block of wood has its own unique properties that must be judged and worked on its own terms. Use spalted wood and your work will never go unnoticed. Use it well, and you’ll produce a real showstopper.


Sources

(Note: Product availability and costs are subject to change since original publication date.)

Flat material suppliers:

Northwest Timber
P.O. Box 1010
Jefferson, OR 97352
541-327-1000


Randel Woods
P.O. Box 96
Randel,WA 98377
360-497-2071


Talarico Hardwoods

RD #3 Box 3268
Mohnton, PA 19540-9339
610-775-0400

 

Bigleaf Maple:

Mount. Cheam Woodworking
8359 Banford Road
Chilliwack, B.C.V20GH3
604-795-9297

 

Turning stock suppliers:

One Good Turn
6064 S. 300 W. #11
Murray, UT 84107
801-266-1578


Choice Woods
833 W. Main St.
Louisville, KY 40202
888-895-7779


Craft Supplies USA

1287 E. 1120 S.
Provo, UT 84606
800-551-8876


Hot Stuff CA Glue
Satellite City, P.O. Box 836
Simi Valley, CA 93062
800-786-0062


P. C. Petrifier
Protective Coatings
221 S. 3rd St.
Allentown, PA 18102
800-220-2103


General Finishes
Sealacell Step 1
P.O. Box 51567
New Berlin,WI 53151
800-888-8286

 

For further reading:

"Sculpting Wood" by Mark
Lindquist, 1986, Worcester, Mass., Davis Publications, 800-533-2847. Mark and his father Mel have been pioneers in working spalted wood and in popularizing its use as a decorative material.

"Understanding Wood" by Bruce Hoadley, 1980, Newtown, Conn., Taunton Press, 800-888-8286.


This story originally appeared in American Woodworker December 1999, issue #77.

December 1999, issue #77

Purchase this back issue.

Click any image to view a larger version.


Cabinet on Stand English oak with spalted bigleaf maple panels by Tim Patterson, student, College of the Redwoods, 1996.





Claro walnut box inlaid with spalted end-grain sycamore, bookmatched to form a bird image by Del Stubbs, 1982.


An active fungus colony surrounds itself with a chemical and physical barrier that defines its outer boundaries. Filaments of the fungus pack and swell in these regions and exude generous amounts of pigmented material that usually appear as black lines. The material in these “zone lines” protects the colony from attack by bacteria, insects, and other fungi, and assists in maintaining a desirably moist atmosphere. Inset: Electron microscope view of a fungus zone line in front of wood cell structures.



Worm-spalted red maple bowl by Alan Lacer, 1998. Typical spalting differs from worm spalt, where the worm hole allows the fungus to enter and work from the inside out.



Working Spalted Wood Safely

There is anecdotal and some medical evidence that substances from decaying wood are a health threat. Allergic reactions and some serious lung diseases have been traced to spores and fungi that inhabit rotting wood. The effect on an individual woodworker depends on his or her tolerance to the spores and fungi, the concentration of them in the environment and the length of exposure. Persons with weakened immune systems, lung illnesses or who show signs of allergic reactions to the spalted wood should avoid the material altogether. One must err on the side of caution when working spalted wood. Freshly sawn green material with active spores and fungi, or even air-dried material, is potentially the most hazardous. Kiln drying, by turning up the heat and driving out the moisture, will actually kill both fungi and spores. To avoid breathing spalted wood dust, I strongly recommend that you wear a respirator—not a nuisance mask—and have an effective point-of-origin dust collection system or a self-contained air filtration helmet. Avoid prolonged contact with your skin, and clean your work area thoroughly following any work with spalted wood.

 

Spalted Wood

Spalted Wood

By Alan Lacer


When wood is captured somewhere between the extremes of being completely sound and fully rotten, it can display magnificent beauty. The discoloration, prominent black lines and changes in texture that occur during the decaying process are known to woodworkers as spalting.

Spalting is a by-product of the rotting process that is carried out by a vast army of stain, mold and decay fungi. They are abundantly present in the air and soil, waiting for favorable conditions and a suitable host. Generally, wood moisture content of at least 25 percent, temperatures from about 40- to 90-degrees F, air and food (especially abundant in sap wood) are what the fungi need. A tree or branch freshly fallen onto a damp forest floor in warm weather is asking for it.

Lighter colored woods offer the best canvas for nature’s graphic work. Hard maple is viewed as the king of spalted woods, although sycamore, persimmon, red and white oak, elm, pecan, birch, buckeye, apple, magnolia, beech, holly, hackberry, box elder and the sapwoods of walnut and cocobolo are favored by woodworkers as well.


Where to find spalted wood

You can purchase spalted wood—usually maple—from specialty lumber and mail order suppliers (see Sources, below). Turning blocks are most easily found, but a few suppliers offer boards when they can get them.

Hunting spalted wood is like panning for gold—lots of searching for that one precious nugget. Logs rotting on the forest floor, dead limbs and entire dead standing trees are excellent sources. You can also hunt for hidden treasure at a community bone yard of removed trees, and don’t overlook the bottom of your old firewood pile.


Make your own spalted wood

Woodworkers commonly use these methods to cause wood to spalt. They will work most effectively if the temperature is kept where the fungi will thrive, between 60- and 80-degrees F. Monitor the spalting progress monthly—the optimal conditions you’ve created can make it happen fast.

• Place a freshly cut log section 2 to 3 ft. long upright on the bare ground. Put a shovel of dirt on the top end and cover it loosely with black plastic.

• Bury a log, freshly sawn green boards or green rough-turned bowls in damp sawdust containing pieces of rotten wood with active fungi. Keep the sawdust moist.

• Use plastic bags or plastic garbage cans to hold short sections of green wood or rough-turned bowls. Adding some soil or rotting sawdust may speed the process, although the fungi already present in the air or on the wood surface is probably enough to get it going. Leave the bags or cans with a small opening to allow for some air exchange.


How to stabilize spalted wood

Remove those things the fungi need to grow, and you’ll stop its progress. One method is to lower the wood’s moisture content.Wood below 25-percent moisture content, when kept in low relative humidity, is not likely to decay or even stain. Accomplish this by air or kiln drying, placing smaller pieces in a microwave or finish turning if the piece was a rough-turned bowl. You can also raise or lower the wood’s temperature. Spalting rarely occurs above 90-degrees F and stops below 32-degrees F. Some turners store blanks in a freezer prior to finish turning. Finally, you can restrict the air—no air, no decay. Logs submerged in water, for example, do not decompose from fungi. Tightly wrapping the wood in several layers of plastic will restrict the air and slow the growth of the fungi.

 

Working properties

If you’re lucky, you’ll catch the spalting at the right time, before the cellular structure of the wood deteriorates, and you’ll be able to work the piece without any trouble. Sometimes, however, the material will have areas that have become soft and punky. These areas have no strength and defy normal woodworking strategies. They will crumble, tear out in chunks or leave a wrinkled appearance when you try to cut or plane them. They refuse to be glued together, and leave you with a cratered, uneven surface when you try to sand. Though not suitable for joinery, these soft areas can often be stiffened enough to finish so the piece of wood can still be used decoratively.

You can saturate soft areas with a liquid hardener. Where the wood is only marginally soft, a spot coat or two of clear shellac or nitrocellulose sanding sealer may harden it sufficiently. A really punky spot will require cyanoacrylate (CA) glue (the thin, watery type) or a product made to stabilize rotten wood. There are a number of them sold as wood hardeners at hardware stores. It may take several generous applications to treat each bad spot. These hardeners are effective, but they have side effects. They fill the wood cells, so surfaces treated with them can’t be glued and oil finishes don’t take well because they can’t penetrate. Solvent-based hardeners and CA glues darken the wood considerably. I like Protective Coatings Petrifier (see Sources, below). It’s a water-based hardener that doesn’t discolor the wood, yet seals and stiffens effectively. It’s an excellent choice for troublesome soft spots.

You should be able to work the stiffened surface with edge tools—make very light cuts—or with abrasives, taking care to provide a firm, flat backing for the sandpaper. Some turners use body grinders or stiffbacked sanding discs and work the piece while it’s spinning on the lathe. For flat lumber, an abrasive planer is an excellent option, followed by a randomorbit or pad sander. If you sand by hand, use a sanding block to give firm support to the paper.

 

Finishing

You are likely to encounter three problems when you finish spalted wood: Splotching, yellowing and excessive darkening. The whiter woods—which usually have the most dramatic examples of spalting—can turn quite yellow with certain finishes, and because the soft areas act like end-grain or even a sponge, splotching or excessive darkening can result unless the piece is sealed first. An effective weapon against splotching is clear, dewaxed shellac used as a sealer. (Spray cans of shellac are thinned and dewaxed.) Cover the entire piece with a thin coat and let it dry. Then recoat dull-looking areas until all surfaces have a uniform sheen. You can use almost any finish as a topcoat over dewaxed shellac after it’s been sanded.

To minimize yellowing and darkening, use a surfacefilm finish like clear shellac or lacquer. Waterborne finishes dry clear and don’t yellow with age. If the piece is primarily decorative and has few, if any, soft areas, clear wax is appropriate.

If you don’t mind the yellowing and darkening, use your favorite oil finish, but be prepared to make many applications to the softer areas. Experience has taught me that an oil-finished spalted piece will appear rather muddy and uneven at first, but will look better as the finish cures, which can take weeks or even months. Some oil finishes (such as General Finishes Sealacell Step 1, see Sources, below) are essentially a thinned, light-colored varnish, and will not yellow as much.

If you are looking for a challenge, and effects that often surpass the wildest woods from the tropics, spalted wood may be your ticket. Each block of wood has its own unique properties that must be judged and worked on its own terms. Use spalted wood and your work will never go unnoticed. Use it well, and you’ll produce a real showstopper.


Sources

(Note: Product availability and costs are subject to change since original publication date.)

Flat material suppliers:

Northwest Timber
P.O. Box 1010
Jefferson, OR 97352
541-327-1000


Randel Woods
P.O. Box 96
Randel,WA 98377
360-497-2071


Talarico Hardwoods

RD #3 Box 3268
Mohnton, PA 19540-9339
610-775-0400

 

Bigleaf Maple:

Mount. Cheam Woodworking
8359 Banford Road
Chilliwack, B.C.V20GH3
604-795-9297

 

Turning stock suppliers:

One Good Turn
6064 S. 300 W. #11
Murray, UT 84107
801-266-1578


Choice Woods
833 W. Main St.
Louisville, KY 40202
888-895-7779


Craft Supplies USA

1287 E. 1120 S.
Provo, UT 84606
800-551-8876


Hot Stuff CA Glue
Satellite City, P.O. Box 836
Simi Valley, CA 93062
800-786-0062


P. C. Petrifier
Protective Coatings
221 S. 3rd St.
Allentown, PA 18102
800-220-2103


General Finishes
Sealacell Step 1
P.O. Box 51567
New Berlin,WI 53151
800-888-8286

 

For further reading:

"Sculpting Wood" by Mark
Lindquist, 1986, Worcester, Mass., Davis Publications, 800-533-2847. Mark and his father Mel have been pioneers in working spalted wood and in popularizing its use as a decorative material.

"Understanding Wood" by Bruce Hoadley, 1980, Newtown, Conn., Taunton Press, 800-888-8286.


This story originally appeared in American Woodworker December 1999, issue #77.

December 1999, issue #77

Purchase this back issue.

Click any image to view a larger version.


Cabinet on Stand English oak with spalted bigleaf maple panels by Tim Patterson, student, College of the Redwoods, 1996.





Claro walnut box inlaid with spalted end-grain sycamore, bookmatched to form a bird image by Del Stubbs, 1982.


An active fungus colony surrounds itself with a chemical and physical barrier that defines its outer boundaries. Filaments of the fungus pack and swell in these regions and exude generous amounts of pigmented material that usually appear as black lines. The material in these “zone lines” protects the colony from attack by bacteria, insects, and other fungi, and assists in maintaining a desirably moist atmosphere. Inset: Electron microscope view of a fungus zone line in front of wood cell structures.



Worm-spalted red maple bowl by Alan Lacer, 1998. Typical spalting differs from worm spalt, where the worm hole allows the fungus to enter and work from the inside out.



Working Spalted Wood Safely

There is anecdotal and some medical evidence that substances from decaying wood are a health threat. Allergic reactions and some serious lung diseases have been traced to spores and fungi that inhabit rotting wood. The effect on an individual woodworker depends on his or her tolerance to the spores and fungi, the concentration of them in the environment and the length of exposure. Persons with weakened immune systems, lung illnesses or who show signs of allergic reactions to the spalted wood should avoid the material altogether. One must err on the side of caution when working spalted wood. Freshly sawn green material with active spores and fungi, or even air-dried material, is potentially the most hazardous. Kiln drying, by turning up the heat and driving out the moisture, will actually kill both fungi and spores. To avoid breathing spalted wood dust, I strongly recommend that you wear a respirator—not a nuisance mask—and have an effective point-of-origin dust collection system or a self-contained air filtration helmet. Avoid prolonged contact with your skin, and clean your work area thoroughly following any work with spalted wood.

 

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